There are four deposit types related to a Permian mafic complex in northern Xinjiang, i.e., copper-nickel sulfide deposit, vanadic titanomagnetite deposit, magnetite （-cobalt） deposit and Cu-Ni- VTiFe composite depo...There are four deposit types related to a Permian mafic complex in northern Xinjiang, i.e., copper-nickel sulfide deposit, vanadic titanomagnetite deposit, magnetite （-cobalt） deposit and Cu-Ni- VTiFe composite deposit. The deposits are distributed spanning tectonic units with close and consecutive metallogenic ages. A transitional deposit type can occur among the end-member deposits. Trace elements of host rocks show that they can derive from similar source area. Hence, they constitute a particular metallogenic series related to a mafic-ultramafic complex that is also a symbol series of the post-collisional stage of the Central Asia Metallogenic Province （CAMP）. The metallogenic ages of the series are between 260 Ma and 300 Ma throughout the Permian. Unlike mineralization from a mantle plume, the metallogenic period of this series spans at least 40 Ma. Compared with related deposits of the Emeishan mantle plume, the North Xinjiang series has a similar ore-forming element assemblage but has preferably developed Cu-Ni sulfide deposits rather than vanadic titanomagnetite deposits. In concomitance with this series, North Xinjiang area has developed a set of syntectonic Au-Cu-Mo metallogenic series related to a felsic volcanic-intrusive complex, which might indicate that there is no direct relationship with mantle plume activity. From early to late, i.e., the sequence of copper-nickel sulfide to magnetite （-cobalt） to vanadic titanomagnetite deposit, the host rock series evolves from mafic-ultramafic and tholeiite series to mafic and alkalic series, the ~REE content tends to increase with increasing of REE fractionation, and some of the trace elements （particularly LIL） also show an increasing tendency. The above evolutionary regularity possibly reflects a course where the magma source deepens and thermal interface moves down, energy gradually exhausts, and neo-continental crust forming in the postcollision stage tends to stabilize.展开更多
Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and i...Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and industry. Drought is caused by an imbalance between the inputs of and the demand for water which is insufficient to meet the demands of human activities and the eco-environment. As a major arid and semi-arid area and an important agricultural region in Northwest China, North Xinjiang （NX） shows great vulnerability to drought. In this paper, the characteristics of inter-annual and seasonal drought were analyzed in terms of drought occurrence and drought coverage, by using the composite index of meteorological drought and the data of daily precipitation, air temperature, wind speed, relative humidity and sunshine duration from 38 meteorological stations during the period 1961-2012. Trend analysis, wavelet analysis and empirical orthogonal function were also applied to investigate change trend, period and regional characteristics, respectively. In NX, annual and seasonal drought occurrence and drought coverage all showed a decreasing trend that was most significant in winter （with rates of-0.26 month/10a and -15.46%, respectively）, and drought occurrence in spring and summer were more frequent than that in autumn and winter. Spatially, drought was severe in eastern regions but mild in western regions of NX. Annual and seasonal drought occurrence at 38 meteorological stations displayed decreasing trends and were most significant in ＂Shi- hezi-Urumqi-Changji＂, which can help to alleviate severe drought hazards for local agricultural production and improve human livelihood. NX can be approximately classified into three sub-regions （severe drought region, moder- ate drought region and mild drought region）, which were calculated from annual drought frequencies. The cross wavelet transform suggested that SOl （Southern Oscillation Index）, AOI （Arctic Oscillation Index）, AAOI （Antarctic Oscillation Index）, PAOI （Pacific/North American Oscillation Index） and NAOI （North Atlantic Oscillation Index） have significant correlation with the variation of drought occurrence in NX. To prevent and mitigate the occurrence of drought disasters in NX, agricultural and government managers should pay more attention to those drought events that occur in spring and summer.展开更多
Platinum group element （PGE） mineralization is mostly related to mafc--ultramafic complexes of the dominant magmatic deposit type. Mineralization of this type mainly relies on two conditions： the abundance of PGE i...Platinum group element （PGE） mineralization is mostly related to mafc--ultramafic complexes of the dominant magmatic deposit type. Mineralization of this type mainly relies on two conditions： the abundance of PGE in magma, and the presence of mechanisms favorable to PGE enrich- ment and separation from sulfur-saturated magma during magmatic evolution. Mafic-ultramafic complexes are widely developed in North Xinjiang, including （1） the large-scale copper-nickel deposits of Kelatongke, Huangshan, Huangshan East, and Tulargen, （2） numerous small to medium-sized copper- nickel deposits such as Xiangshan, Tudun, Hulu, Baishiquan, and （3） the Xiangshan West and Weiya medium-sized V--Ti magnetite deposits. However, mafic-ultramafic complexes in North Xinjiang rarely form PGE deposits. Therefore, questions about PGE metallogenesis in North Xinjiang are discussed in this paper from the standpoint of the ore-forming mechanism of PGE deposits and the characteristics of the North Xinjiang magma sources. The rock types of the post-collisional mafic--ultramafic complexes in North Xinjiang are of a ferrous rock series formed by fractional crystallization, a rock type generally favorable for hosting PGE. For the Cu-Ni sulfde deposits of North Xingjiang, the assimilation of crustal material causes sulfide liquation during processes of magmatic evolution and mineralization. This can be shown petrogeochemically, including the characteristics of Sr, Nd, Pb, O, Os, and S isotopes, which indi- cate a magmatic ore-forming mechanism for the Xingjiang PGE deposits. The principal reason for weak PGE mineralization in North Xinjiang may be ascribed to a widely-developed depleted mantle source （with positive end values） that underlies it. The North Xinjiang lithosphere is not of typical Precambrian cratonal type, but has more affinities with modified oceanic lithosphere or immature continental lithosphere that would constitute PGE-poor original magma sources unfavorable to PGE mineralization.展开更多
Reference crop evapotranspiration (ET_0) is a critical part in water cycle and water balance of ecosystem, which is greatly important to effective utilization of agricultural water resources and for making reasonable ...Reference crop evapotranspiration (ET_0) is a critical part in water cycle and water balance of ecosystem, which is greatly important to effective utilization of agricultural water resources and for making reasonable irrigation system. In order to propose a suitable method for computing ET_0 in North Xinjiang, based on daily meteorological data from May 1 to September30, 2010 provided by Weather Station of Fuhai County, we used FAO56 Penman-Monteith as the standard formula to compute ET_0, compared the differences and relations between such the method and other 4 calculation formulas, and analyzed the cause of the deviation, finally evaluated the applicability of computational method in North Xinjiang. The results showed that the calculation results by FA056 PM Method was approximate to that by FAO Penman method and IA method, of which the relative error was 9.26% and 13.51% respectively, the ET_0 results calculated by PT method and HS method were generally greater than the results by FAO56 PM, and their deviation was very obvious.展开更多
Objective The Early Permian mafic-ultramafic intrusions （298- 270 Ma, Mao et al., 2008）, which are widely distributed in different tectonic domains in North Xinjiang, host magmatic sulfide ore deposits, making Nort...Objective The Early Permian mafic-ultramafic intrusions （298- 270 Ma, Mao et al., 2008）, which are widely distributed in different tectonic domains in North Xinjiang, host magmatic sulfide ore deposits, making North Xinjiang the second most important region for Ni resources in China. The bulk of Cu-Ni ore deposits in East Tianshan, making up a large portion of Ni resources in North Xinjiang, were concentrated in the east of East Tianshan （the Huangshan- Jing＇erquan region） （Feng Yanqing, et al., 2017）, while no any analogue was discovered in the west of East Tianshan until the Lubei Cu-Ni （Co） ore deposit （90°21＇E, 42°10rN） was identified by Xinjiang Geological Survey in 2014. The Lubei Cu-Ni （Co） ore deposit is a medium- to large- sized deposit with Ni and Cu grades in the range 0.2%- 7.76% and 0.2%-2.30%, respectively. This work has initiated the prospection for a large-sized Cu-Ni ore deposit in the west of East Tianshan.展开更多
The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene g...The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg+Fe^2+),and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg+Fe^2+), Al2O3 and depletion of U, Th and Rbcontents. The AG has moderate ∑REE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG may be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750℃-780℃ and 0.6-0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.展开更多
[Objective] The aim was to study climate changes in northern Tianshan in Xinjiang and its influences on runoff. [Methed] Based on the runoff data for 54 years of Kenswatt station on Manas River and the climate date of...[Objective] The aim was to study climate changes in northern Tianshan in Xinjiang and its influences on runoff. [Methed] Based on the runoff data for 54 years of Kenswatt station on Manas River and the climate date of 16 meteorological stations from 1957 to 2007 in the north of Tian- shan in Xinjiang, the climate change and temporal series of the annual runoff were studied by use of nonparametric test, wavelet analysis, R/S analysis and periodic trend superposition model. [ Result] The temperature, precipitation and annual runoff of Manas River increased significantly. The Hurst coefficients of both climate factors and the annual runoff were bigger than 0.5, which indicated that they would still keep an increasing trend. Temperature from 1957 to 1959 was low, precipitation was much, belonging to low temperature and more rain period. 1960s and 1970s were low temperature and less rain period. Temperature in 1980s was close to average value and precipitation was little. Since 1990s, it entered into high temperature and less rain period and was significant during 2000 and 2007. The temperature and precipitation changed in 1995 and 1996. Tempera- ture was＇significant in 11 and 22 years. Precipitation had 5, 8, 14 and 22 years of main cycle. The annual runoff and climate factors in Manasi River were increasing in different times. The annual runoff was related to climate factors, and temperature was closer to annual runoff than precipitation. [ Conclusion] The study provided theoretical basis for the reasonable configuration, ecological protection and agricultural production of water re- sources in north Tianshan in Xinjiang.展开更多
By applying the empirical Green’s function method, we first proved that the source spectra in the middle eastern area of North Tianshan follow the ω -2 Brune model, and then, on this basis, obtained the source spect...By applying the empirical Green’s function method, we first proved that the source spectra in the middle eastern area of North Tianshan follow the ω -2 Brune model, and then, on this basis, obtained the source spectra for 105 earthquakes of ML 2.5～5.7 in the studied area upon removing the noise, instrument, propagation and site effects in the observational seismic S waveforms. Finally, we determined the source parameters such as the seismic moment, stress drop, source dimension, etc., based on the Brune model. The results show that there is a good linear correlation between scalar seismic moment, M0, and ML, which is Log 10 M0=1.10 ML + 17.20; The source radii range between 100～1500m; the stress drop, 1～16MPa with a predominant range of 1～10MPa. The relationship of the seismic moment versus corner frequencies indicates that there may exist two source scaling, that is, when M0<4×10 21 dyne5cm （equal to an ML4.0 event）, stress drop is weakly dependent on M0; whereas, when M0>4×10 21 dyne5cm, stress drop is independent of M0.展开更多
Snow disaster is one of the top ten natural disasters worldwide. Almost every year, there will be snow disasters in north Xinjiang, northwestern China. Since the accumulated heavy snow in winter season will seriously ...Snow disaster is one of the top ten natural disasters worldwide. Almost every year, there will be snow disasters in north Xinjiang, northwestern China. Since the accumulated heavy snow in winter season will seriously threaten people’s lives, the main object of this study is to produce a potential hazard map for snow avalanche prevention. Taking three snow seasons from November to March of year 2008 to 2010, potential hazard areas were estimated, based on snow volume products and terrain features. Remote sensing (RS) techniques and geographical information system (GIS) based weighted linear combination (WLC) approach were applied, taking into consideration multiple criteria. Snow avalanche risks were analyzed using physical exposure and vulnerability indexes. The analysis indicates that: the areas at high-risk of avalanches are located in the north and south part of the counties of Altay, Bortala and Ili prefectures;the areas at medium-risk of avalanches are found in the certain part of Altay prefecture and Urumqi, Changji, Tacheng prefectures;the avalanche risk is generally low throughout the large area to the certain part of the study area and the region on the border of the eastern north Xinjiang. Overall, the risks of snow avalanche in Altay and Ili prefectures are higher than that other regions;those areas should be allocated correspondingly more salvage materials.展开更多
More than 200 upper and lower jaws of ochotonid were found in the Late Oligocene of thenorthern part of the Junggar Basin,Xinjiang Uygur Autonomous Region,in the summer of1982.Sinolagomys.a unique Paleogene lagomorph ...More than 200 upper and lower jaws of ochotonid were found in the Late Oligocene of thenorthern part of the Junggar Basin,Xinjiang Uygur Autonomous Region,in the summer of1982.Sinolagomys.a unique Paleogene lagomorph with rootless(?) cheek teeth,was erected byBohlin(1937)based on the collections from Shargaltien and Taben-buluk,Gansu province.Upto now,it has been recorded from Middle Oligocene to the Lower Miocene of Gansu,Ninxia,Nei Mongol,and Xinjiang of China,and the Mongolian People’s Republic.展开更多
文摘There are four deposit types related to a Permian mafic complex in northern Xinjiang, i.e., copper-nickel sulfide deposit, vanadic titanomagnetite deposit, magnetite （-cobalt） deposit and Cu-Ni- VTiFe composite deposit. The deposits are distributed spanning tectonic units with close and consecutive metallogenic ages. A transitional deposit type can occur among the end-member deposits. Trace elements of host rocks show that they can derive from similar source area. Hence, they constitute a particular metallogenic series related to a mafic-ultramafic complex that is also a symbol series of the post-collisional stage of the Central Asia Metallogenic Province （CAMP）. The metallogenic ages of the series are between 260 Ma and 300 Ma throughout the Permian. Unlike mineralization from a mantle plume, the metallogenic period of this series spans at least 40 Ma. Compared with related deposits of the Emeishan mantle plume, the North Xinjiang series has a similar ore-forming element assemblage but has preferably developed Cu-Ni sulfide deposits rather than vanadic titanomagnetite deposits. In concomitance with this series, North Xinjiang area has developed a set of syntectonic Au-Cu-Mo metallogenic series related to a felsic volcanic-intrusive complex, which might indicate that there is no direct relationship with mantle plume activity. From early to late, i.e., the sequence of copper-nickel sulfide to magnetite （-cobalt） to vanadic titanomagnetite deposit, the host rock series evolves from mafic-ultramafic and tholeiite series to mafic and alkalic series, the ~REE content tends to increase with increasing of REE fractionation, and some of the trace elements （particularly LIL） also show an increasing tendency. The above evolutionary regularity possibly reflects a course where the magma source deepens and thermal interface moves down, energy gradually exhausts, and neo-continental crust forming in the postcollision stage tends to stabilize.
基金supported by International Science & Technology Cooperation Program of China (2010DFA92720)the Scientific Innovation Research Project for Graduate Students of XinjiangSoil Science Key Discipline Project of Xinjiang Uygur Autonomous Region
文摘Drought, which is one of the most frequently occurring severe hazards with long time scales and cov- ering wide geographical areas, is a natural phenomenon resulting in significant economic losses in agriculture and industry. Drought is caused by an imbalance between the inputs of and the demand for water which is insufficient to meet the demands of human activities and the eco-environment. As a major arid and semi-arid area and an important agricultural region in Northwest China, North Xinjiang （NX） shows great vulnerability to drought. In this paper, the characteristics of inter-annual and seasonal drought were analyzed in terms of drought occurrence and drought coverage, by using the composite index of meteorological drought and the data of daily precipitation, air temperature, wind speed, relative humidity and sunshine duration from 38 meteorological stations during the period 1961-2012. Trend analysis, wavelet analysis and empirical orthogonal function were also applied to investigate change trend, period and regional characteristics, respectively. In NX, annual and seasonal drought occurrence and drought coverage all showed a decreasing trend that was most significant in winter （with rates of-0.26 month/10a and -15.46%, respectively）, and drought occurrence in spring and summer were more frequent than that in autumn and winter. Spatially, drought was severe in eastern regions but mild in western regions of NX. Annual and seasonal drought occurrence at 38 meteorological stations displayed decreasing trends and were most significant in ＂Shi- hezi-Urumqi-Changji＂, which can help to alleviate severe drought hazards for local agricultural production and improve human livelihood. NX can be approximately classified into three sub-regions （severe drought region, moder- ate drought region and mild drought region）, which were calculated from annual drought frequencies. The cross wavelet transform suggested that SOl （Southern Oscillation Index）, AOI （Arctic Oscillation Index）, AAOI （Antarctic Oscillation Index）, PAOI （Pacific/North American Oscillation Index） and NAOI （North Atlantic Oscillation Index） have significant correlation with the variation of drought occurrence in NX. To prevent and mitigate the occurrence of drought disasters in NX, agricultural and government managers should pay more attention to those drought events that occur in spring and summer.
基金supported by Major State Basic Research Program of the People's Republic of China(Nos.2007CB411304 and 2001CB409806)
文摘Platinum group element （PGE） mineralization is mostly related to mafc--ultramafic complexes of the dominant magmatic deposit type. Mineralization of this type mainly relies on two conditions： the abundance of PGE in magma, and the presence of mechanisms favorable to PGE enrich- ment and separation from sulfur-saturated magma during magmatic evolution. Mafic-ultramafic complexes are widely developed in North Xinjiang, including （1） the large-scale copper-nickel deposits of Kelatongke, Huangshan, Huangshan East, and Tulargen, （2） numerous small to medium-sized copper- nickel deposits such as Xiangshan, Tudun, Hulu, Baishiquan, and （3） the Xiangshan West and Weiya medium-sized V--Ti magnetite deposits. However, mafic-ultramafic complexes in North Xinjiang rarely form PGE deposits. Therefore, questions about PGE metallogenesis in North Xinjiang are discussed in this paper from the standpoint of the ore-forming mechanism of PGE deposits and the characteristics of the North Xinjiang magma sources. The rock types of the post-collisional mafic--ultramafic complexes in North Xinjiang are of a ferrous rock series formed by fractional crystallization, a rock type generally favorable for hosting PGE. For the Cu-Ni sulfde deposits of North Xingjiang, the assimilation of crustal material causes sulfide liquation during processes of magmatic evolution and mineralization. This can be shown petrogeochemically, including the characteristics of Sr, Nd, Pb, O, Os, and S isotopes, which indi- cate a magmatic ore-forming mechanism for the Xingjiang PGE deposits. The principal reason for weak PGE mineralization in North Xinjiang may be ascribed to a widely-developed depleted mantle source （with positive end values） that underlies it. The North Xinjiang lithosphere is not of typical Precambrian cratonal type, but has more affinities with modified oceanic lithosphere or immature continental lithosphere that would constitute PGE-poor original magma sources unfavorable to PGE mineralization.
基金Supported by Key Scientific and Technological Research and Development Program of Xinjiang(201531115)Special Fund for Scientific Research of China Institute of Water Resources and Hydropower Research(MK2016J10)
文摘Reference crop evapotranspiration (ET_0) is a critical part in water cycle and water balance of ecosystem, which is greatly important to effective utilization of agricultural water resources and for making reasonable irrigation system. In order to propose a suitable method for computing ET_0 in North Xinjiang, based on daily meteorological data from May 1 to September30, 2010 provided by Weather Station of Fuhai County, we used FAO56 Penman-Monteith as the standard formula to compute ET_0, compared the differences and relations between such the method and other 4 calculation formulas, and analyzed the cause of the deviation, finally evaluated the applicability of computational method in North Xinjiang. The results showed that the calculation results by FA056 PM Method was approximate to that by FAO Penman method and IA method, of which the relative error was 9.26% and 13.51% respectively, the ET_0 results calculated by PT method and HS method were generally greater than the results by FAO56 PM, and their deviation was very obvious.
基金supported by the Geological Survey of China(grant No.DD20160007)
文摘Objective The Early Permian mafic-ultramafic intrusions （298- 270 Ma, Mao et al., 2008）, which are widely distributed in different tectonic domains in North Xinjiang, host magmatic sulfide ore deposits, making North Xinjiang the second most important region for Ni resources in China. The bulk of Cu-Ni ore deposits in East Tianshan, making up a large portion of Ni resources in North Xinjiang, were concentrated in the east of East Tianshan （the Huangshan- Jing＇erquan region） （Feng Yanqing, et al., 2017）, while no any analogue was discovered in the west of East Tianshan until the Lubei Cu-Ni （Co） ore deposit （90°21＇E, 42°10rN） was identified by Xinjiang Geological Survey in 2014. The Lubei Cu-Ni （Co） ore deposit is a medium- to large- sized deposit with Ni and Cu grades in the range 0.2%- 7.76% and 0.2%-2.30%, respectively. This work has initiated the prospection for a large-sized Cu-Ni ore deposit in the west of East Tianshan.
文摘The basic granulite of the Altay orogenic belt occurs as tectonic lens in the Devonian medium- to lower-grade metamorphic beds through fault contact. The Altay granulite (AG) is an amphibole plagioclase two-pyroxene granulite and is mainly composed of two pyroxenes, plagioclase, amphibole and biotite. Its melano-minerals are rich in Mg/(Mg+Fe^2+),and its amphibole and biotite are rich in TiO2. The AG is rich in Mg/(Mg+Fe^2+), Al2O3 and depletion of U, Th and Rbcontents. The AG has moderate ∑REE and LREE-enriched with weak positive Eu anomaly. The AG shows island-arc pattern with negative Nb, P and Ti anomalies, reflecting that formation of the AG may be associated with subduction. Geochemical and mineral composition data reflect that the protolith of the AG is calc-alkaline basalt and formed by granulite facies metamorphism having peak P-T conditions of 750℃-780℃ and 0.6-0.7 Gpa. The AG formation underwent two stages was suggested. In the early stage of oceanic crustal subduction, calc-alkaline basalt with island-arc environment underwent granulite facies metamorphism to form the AG in deep crust, and in the late stage, the AG was thrust into the upper crust.
基金Supported by National Key Fundamental Research Development (937 Plan) (2010CB-951003)
文摘[Objective] The aim was to study climate changes in northern Tianshan in Xinjiang and its influences on runoff. [Methed] Based on the runoff data for 54 years of Kenswatt station on Manas River and the climate date of 16 meteorological stations from 1957 to 2007 in the north of Tian- shan in Xinjiang, the climate change and temporal series of the annual runoff were studied by use of nonparametric test, wavelet analysis, R/S analysis and periodic trend superposition model. [ Result] The temperature, precipitation and annual runoff of Manas River increased significantly. The Hurst coefficients of both climate factors and the annual runoff were bigger than 0.5, which indicated that they would still keep an increasing trend. Temperature from 1957 to 1959 was low, precipitation was much, belonging to low temperature and more rain period. 1960s and 1970s were low temperature and less rain period. Temperature in 1980s was close to average value and precipitation was little. Since 1990s, it entered into high temperature and less rain period and was significant during 2000 and 2007. The temperature and precipitation changed in 1995 and 1996. Tempera- ture was＇significant in 11 and 22 years. Precipitation had 5, 8, 14 and 22 years of main cycle. The annual runoff and climate factors in Manasi River were increasing in different times. The annual runoff was related to climate factors, and temperature was closer to annual runoff than precipitation. [ Conclusion] The study provided theoretical basis for the reasonable configuration, ecological protection and agricultural production of water re- sources in north Tianshan in Xinjiang.
文摘By applying the empirical Green’s function method, we first proved that the source spectra in the middle eastern area of North Tianshan follow the ω -2 Brune model, and then, on this basis, obtained the source spectra for 105 earthquakes of ML 2.5～5.7 in the studied area upon removing the noise, instrument, propagation and site effects in the observational seismic S waveforms. Finally, we determined the source parameters such as the seismic moment, stress drop, source dimension, etc., based on the Brune model. The results show that there is a good linear correlation between scalar seismic moment, M0, and ML, which is Log 10 M0=1.10 ML + 17.20; The source radii range between 100～1500m; the stress drop, 1～16MPa with a predominant range of 1～10MPa. The relationship of the seismic moment versus corner frequencies indicates that there may exist two source scaling, that is, when M0<4×10 21 dyne5cm （equal to an ML4.0 event）, stress drop is weakly dependent on M0; whereas, when M0>4×10 21 dyne5cm, stress drop is independent of M0.
文摘Snow disaster is one of the top ten natural disasters worldwide. Almost every year, there will be snow disasters in north Xinjiang, northwestern China. Since the accumulated heavy snow in winter season will seriously threaten people’s lives, the main object of this study is to produce a potential hazard map for snow avalanche prevention. Taking three snow seasons from November to March of year 2008 to 2010, potential hazard areas were estimated, based on snow volume products and terrain features. Remote sensing (RS) techniques and geographical information system (GIS) based weighted linear combination (WLC) approach were applied, taking into consideration multiple criteria. Snow avalanche risks were analyzed using physical exposure and vulnerability indexes. The analysis indicates that: the areas at high-risk of avalanches are located in the north and south part of the counties of Altay, Bortala and Ili prefectures;the areas at medium-risk of avalanches are found in the certain part of Altay prefecture and Urumqi, Changji, Tacheng prefectures;the avalanche risk is generally low throughout the large area to the certain part of the study area and the region on the border of the eastern north Xinjiang. Overall, the risks of snow avalanche in Altay and Ili prefectures are higher than that other regions;those areas should be allocated correspondingly more salvage materials.
文摘More than 200 upper and lower jaws of ochotonid were found in the Late Oligocene of thenorthern part of the Junggar Basin,Xinjiang Uygur Autonomous Region,in the summer of1982.Sinolagomys.a unique Paleogene lagomorph with rootless(?) cheek teeth,was erected byBohlin(1937)based on the collections from Shargaltien and Taben-buluk,Gansu province.Upto now,it has been recorded from Middle Oligocene to the Lower Miocene of Gansu,Ninxia,Nei Mongol,and Xinjiang of China,and the Mongolian People’s Republic.
